Always have used one and never without. It has all my 'stuff' in it - ranging from whiz wheels, copies of relevant IAL plates for the area, aircraft timing log sheets, make up, etc. And with my current a/c, a BK, I have it on my right thigh to lift my wrist up to hold the cyclic better. No set type, used hard and soft ones. Having one that you can easily view the plate is better in my opinion.
